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</a></div> <!----></nav> <ul class="sidebar-links"><li><a href="/blog-666group/blogs/fanzhixuan/one.html" aria-current="page" class="active sidebar-link">js数组的基本方法</a></li><li><a href="/blog-666group/blogs/fanzhixuan/two.html" class="sidebar-link">js的循环机制、宏观任务与微观任务</a></li></ul> </aside> <div class="password-shadow password-wrapper-in" style="display:none;" data-v-25ba6db2 data-v-1aefc0b4><h3 class="title" data-v-25ba6db2 data-v-25ba6db2>js数组的基本方法</h3> <!----> <label id="box" class="inputBox" data-v-25ba6db2 data-v-25ba6db2><input type="password" value="" data-v-25ba6db2> <span data-v-25ba6db2>Konck! Knock!</span> <button data-v-25ba6db2>OK</button></label> <div class="footer" data-v-25ba6db2 data-v-25ba6db2><span data-v-25ba6db2><i class="iconfont reco-theme" data-v-25ba6db2></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-25ba6db2>vuePress-theme-reco</a></span> <span data-v-25ba6db2><i class="iconfont reco-copyright" data-v-25ba6db2></i> <a data-v-25ba6db2><span data-v-25ba6db2>666</span>
            
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        </a></span></div></div> <div data-v-1aefc0b4><main class="page"><section><div class="page-title"><h1 class="title">js数组的基本方法</h1> <div data-v-f875f3fc><i class="iconfont reco-account" data-v-f875f3fc><span data-v-f875f3fc>666</span></i> <i class="iconfont reco-date" data-v-f875f3fc><span data-v-f875f3fc>2020/8/23</span></i> <!----> <i class="tags iconfont reco-tag" data-v-f875f3fc><span class="tag-item" data-v-f875f3fc>js</span></i></div></div> <div class="theme-reco-content content__default"><hr> <h3 id="js常用的数组方法"><a href="#js常用的数组方法" class="header-anchor">#</a> js常用的数组方法</h3> <p><strong>首先JavaScript中创建数组有两种方式</strong></p> <p>（一）使用 Array 构造函数：</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Array</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//创建一个空数组</span>
<span class="token keyword">var</span> arr2 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Array</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 创建一个包含20项的数组</span>
<span class="token keyword">var</span> arr3 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Array</span><span class="token punctuation">(</span>“lily”<span class="token punctuation">,</span>“lucy”<span class="token punctuation">,</span>“Tom”<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 创建一个包含3个字符串的数组</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p>（二）使用数组字面量表示法：</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr4 <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">//创建一个空数组</span>
<span class="token keyword">var</span> arr5 <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 创建一个包含1项的数组</span>
<span class="token keyword">var</span> arr6 <span class="token operator">=</span> <span class="token punctuation">[</span>“lily”<span class="token punctuation">,</span>“lucy”<span class="token punctuation">,</span>“Tom”<span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 创建一个包含3个字符串的数组</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p><strong>数组的方法有数组原型方法，也有从object对象继承来的方法，这里我们只介绍数组的原型方法，数组原型方法主要有以下这些：</strong></p> <p>1.push() 后增</p> <p>push()方法可以向数组后添加一个新的元素，并返回新数组的长度。</p> <p><strong>末尾添加，返回长度，改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">)</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [1,2,3,4] </span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// 4</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>2.unshift() 前增</p> <p>unshift()可以向数组前添加一个或多个元素，并返回新的长度</p> <p><strong>首部添加，返回长度，改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">unshift</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [0,1,2,3,4]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// 5</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>3.pop() 后删</p> <p>pop() 用于删除并返回最后一个元素。</p> <p><strong>尾部删除，返回被删除的元素，改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">pop</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// 3</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>4.shift() 前删</p> <p>shift() 用于删除并返回首个元素</p> <p><strong>删除首部元素，返回被删元素，改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">shift</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [2,3]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// 1</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>5.splice() 修该删除</p> <p>splice(index,length,增加的元素1,增加的元素2....,增加的元素N) 表示从index开始删除length个元素，并从index开始新增元素1~N，放回被删除的元素组成的数组</p> <p><strong>对数组进行删除修改，返回被删除的元素组成的数组，改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [1,3,[2,3,4],5,3]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// [2]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>6.concat() 拼接</p> <p>concat() 方法用来合并两个或多个数组</p> <p><strong>合并两个或多个数组，返回新数组，不会改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> c <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2,3]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// [4,5]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span> <span class="token comment">// [1,2,3,4,5] </span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>7.slice() 剪切</p> <p>slice(startIndex,endIndex)  返回从startIndex开始(包括)，到endIndex(不包括)之间的原属组成的数组</p> <p><strong>返回新数组，不改变原数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token comment">// 不填参数则表示剪切整个数组  </span>
<span class="token keyword">var</span> c <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token punctuation">)</span> 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2,3] </span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// [1]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span> <span class="token comment">// [1,2,3]    </span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token operator">===</span>c<span class="token punctuation">)</span>  <span class="token comment">// false // 注意 a !== c </span>
 
<span class="token comment">// 负数表示从后往前数</span>
<span class="token keyword">var</span> d <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token operator">-</span><span class="token number">2</span><span class="token punctuation">)</span>   
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>d<span class="token punctuation">)</span> <span class="token comment">// []   从左向右截取，所以说为[]</span>
 
<span class="token keyword">var</span> e <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>  
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">)</span>  <span class="token comment">// [3]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><p>8.join()</p> <p>join() 方法用来将数组转换为字符串</p> <p><strong>不改变原数组，返回转换后的字符串</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>​
<span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">','</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// 1,2,3,4,5</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [1,2,3,4,5]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>9.sort() 排序</p> <p>按ASCLL码排序</p> <p><strong>改变原数组，返回排序后的数组</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span><span class="token string">'b'</span><span class="token punctuation">,</span><span class="token string">'d'</span><span class="token punctuation">,</span><span class="token string">'c'</span><span class="token punctuation">]</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// ['a','b','c','d']</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// ['a','b','c','d']</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><p>10.reverse() 颠倒顺序</p> <p>reverse() 方法用于颠倒数组中元素的顺序。</p> <p><strong>返回的是颠倒后的数组，会改变原数组。</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a  <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">7</span><span class="token punctuation">,</span><span class="token number">6</span><span class="token punctuation">]</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">reverse</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// [6,7,2,3,1]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [6,7,2,3,1]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><p>11.indexOf()和lastIndexOf()</p> <p>indexOf(某元素,startIndex) 从startIndex开始，查找某元素在数组中的位置，若存在，则返回第一个位置的下标,否则返回-1</p> <p>lastIndexOf(某元素，startIndex) 和indexOf()相同，区别在于从尾部向首部查询</p> <p>不会改变原数组，返回找到的index,否则返回-1</p> <p>若不使用下标，则一般通过includes()方法代替indexOf()</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// 2</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// 4</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><p>12.filter() 过滤</p> <p><strong>filter() 方法返回数组中满足条件的元素组成的新数组，原数组不变</strong></p> <p>filter()的参数是一个方法</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">11</span><span class="token punctuation">]</span>
<span class="token comment">// 第一个参数为一个方法，有三个参数，current:当前值 index:当前值下标 array:这个数组对象</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">return</span> current <span class="token operator">&lt;</span> <span class="token number">10</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// [1,2,3,4]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2,3,4,11]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p>13.map() 格式化数组</p> <p><strong>map() 方法来根据需求格式化原数组，返回格式化后的数组。原数组不变</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>
<span class="token comment">// 参数同filter方法</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">return</span> current <span class="token operator">+</span> <span class="token number">1</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// [2,3,4,5,6]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2,3,4,5]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p>14.every()</p> <p>对数组的每一项都运行给定的函数，若每一项都返回 ture,则返回 true</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>

<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">every</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
      <span class="token keyword">return</span> current <span class="token operator">&lt;</span> <span class="token number">6</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token keyword">var</span> c <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">every</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
      <span class="token keyword">return</span> current <span class="token operator">&lt;</span> <span class="token number">3</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// true </span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span>  <span class="token comment">// false </span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><p>15.some()</p> <p>对数组的每一项都运行给定的函数，若存在一项或多项返回 ture,则返回 true</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span>
 
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
       <span class="token keyword">return</span> current <span class="token operator">&gt;</span> <span class="token number">4</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
 
<span class="token keyword">var</span> c <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">current<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
       <span class="token keyword">return</span> current <span class="token operator">&gt;</span> <span class="token number">5</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// true </span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span>  <span class="token comment">// false </span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><p>16.forEach()  数组遍历</p> <p><strong>遍历整个数组，中途不能中断</strong></p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">'a'</span><span class="token punctuation">,</span><span class="token string">'b'</span><span class="token punctuation">,</span><span class="token string">'c'</span><span class="token punctuation">]</span>
<span class="token keyword">var</span> copy <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span>
arr<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">item</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     copy<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span>   
<span class="token punctuation">}</span><span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>copy<span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><p><em><strong>ES6新增的方法</strong></em></p> <p>1.find()</p> <p>找到数组中第一次满足条件的元素，并返回，若找不到则返回undefined。不改变原数组。</p> <p>和filter()方法的区别在于：filter返回值是所有满足条件的元素组成的数组，</p> <p>一般在需要使用找到的元素时，用find()方法</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">]</span>
<span class="token comment">// b在下面需要使用，则一般用find</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">ele<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">return</span> ele <span class="token operator">==</span> <span class="token number">1</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
 
<span class="token keyword">var</span> c <span class="token operator">=</span> <span class="token number">3</span>
<span class="token keyword">var</span> d <span class="token operator">=</span> b <span class="token operator">+</span> c
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// [1,2,3,4]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// 1</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>d<span class="token punctuation">)</span> <span class="token comment">// 4</span>
 
<span class="token comment">// 若只需判断元素是否存在</span>
<span class="token comment">// 若果是简单数组(非对象数组)，则一般使用Array.includes(value)方法</span>
<span class="token comment">// 如果为对象数组，则可以使用Array.some()方法</span>
 
<span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// true</span>
 
<span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">{</span><span class="token string-property property">&quot;name&quot;</span><span class="token operator">:</span> <span class="token string">&quot;xiaoming&quot;</span> <span class="token punctuation">}</span><span class="token punctuation">,</span><span class="token punctuation">{</span><span class="token string-property property">&quot;name&quot;</span><span class="token operator">:</span> <span class="token string">&quot;xiaohong&quot;</span><span class="token punctuation">}</span><span class="token punctuation">]</span>
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">ele</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">return</span> ele<span class="token punctuation">.</span>name <span class="token operator">==</span> <span class="token string">'xiaoming'</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span>                            <span class="token comment">// true</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><p>2.findIndex()方法</p> <p>findIndex()的作用同indexOf()，返回第一个满足条件的下标，并停止寻找。</p> <p>区别是findIndex() 的参数为一个回调函数,且一般用于对象数组</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">]</span>
 
<span class="token keyword">var</span> b <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">ele<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">return</span> ele <span class="token operator">===</span> <span class="token number">2</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
 
<span class="token keyword">var</span> c <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>  
 
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span>  <span class="token comment">// [1,2,3,4]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>  <span class="token comment">// 1</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span>  <span class="token comment">// 1</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><p>3.includes()</p> <p>includes()方法,返回一个布尔值。 参数是一个value,一般用于简单数组。</p> <p>对于复杂数组，则可以使用some()方法替代includes()方法</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">]</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment">// true</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>4.Array.isArray()方法</p> <p>用来判断一个元素是否为数组</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span>  <span class="token comment">// true</span>
Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>  <span class="token comment">// false</span>
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